BREAKTHROUGH discovery by Scots researchers could reveal why
some people are more likely to die from flu than others.

A collaborative study by scientists at Edinburgh University's
Roslin Institute and clinicians at NHS Lothian has shown people not
protected by a certain gene are at risk of potentially life-
threatening reactions to the viruses.
It is the first time researchers have identified a gene which
determines our susceptibility and response to flu and other
infections, and could pave the way for a screening regime to
identify individuals who would benefit from vaccination.
Professor Tim Walsh, a consultant and professor of critical care
medicine at Edinburgh University, said: "Flu can be devastating in
the very young and elderly, but some previously fit young people can
also develop life-threatening lung problems.
"Many young people required prolonged periods in intensive care
during the swine flu pandemic and we had little idea why this small
number of people was so severely affected. This study provides some
clues as to why this may happen.
"It opens avenues for research to develop ways of predicting who
might be at risk and where to focus efforts to find new treatments
for severe viral infections."
The gene - known as IFITM3 - produces a protein that protects
cells against infections. It is believed to be vital for kick-
starting the immune system's battle against viruses such as swine
flu. When present in large quantities, the protein hinders the
spread of the flu virus in the lungs. However, people with the
variant form of the gene cannot produce as much of this defence
protein, thereby leading to a more severe bout of flu.
The study, published in the journal Nature, found patients who
ended up in intensive care with potentially fatal complications
after developing flu were much more likely to have a variant of this
gene, which did not protect against the virus.
The study analysed DNA from patients treated in Scottish
intensive care units during the 2009/10 swine flu pandemic. Blood
samples were taken from the patients who had been previously fit and
healthy.
While the variant is found in only 0.3% of the population, the
scientists found it was present in 5.3% of patients in intensive
care with flu - suggesting it plays a highly significant role in
causing otherwise healthy individuals to fall seriously ill.
Dr Kenneth Baillie, of the Roslin Institute, said: "While most
people who contract flu during a pandemic will recover well and not
experience serious symptoms, some develop a catastrophic and
potentially fatal illness and need to be treated in intensive care.
This happens to otherwise healthy, young people.
"The answer as to why some people become seriously affected by
flu and others don't was a mystery, but this study shows for the
first time it may be because they are more genetically susceptible
to the virus."
The study, launched after the swine flu pandemic arrived in
Scotland in 2009, followed initial research on mice carried out at
the Wellcome Trust Sanger Institute near Cambridge.
The Cambridge studies had already indicated mice with the rarer,
mutant version of IFITM3 were much more likely to have severe
symptoms than mice with the normal version. Now the Scottish
research has shown a parallel relationship between flu and the human
genome.
Professor Paul Kellam, a co-author on the paper and based at the
Wellcome Trust Sanger Institute, said: "This is important for people
who have this variant as we predict their immune infections defences
could be weakened to some virus infections.
"Ultimately, as we learn more about the genetics of
susceptibility to viruses, these people can take informed
precautions, such as vaccinations to prevent infection."